AUTHOR=van der Ree Martijn H. , Cuculich Phillip S. , van Herk Marcel , Hugo Geoffrey D. , Balt Jippe C. , Bates Matthew , Ho Gordon , Pruvot Etienne , Herrera-Siklody Claudia , Hoeksema Wiert F. , Lee Justin , Lloyd Michael S. , Kemme Michiel J. B. , Sacher Frederic , Tixier Romain , Verhoeff Joost J. C. , Balgobind Brian V. , Robinson Clifford G. , Rasch Coen R. N. , Postema Pieter G. 

TITLE=Interobserver variability in target definition for stereotactic arrhythmia radioablation

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2023.1267800

DOI=10.3389/fcvm.2023.1267800

ISSN=2297-055X

ABSTRACT=Background:
Stereotactic arrhythmia radioablation (STAR) is a potential new therapy for patients with refractory ventricular tachycardia (VT). The arrhythmogenic substrate (target) is synthesized from clinical and electro-anatomical information. This study was designed to evaluate the baseline interobserver variability in target delineation for STAR.

Methods:
Delineation software designed for research purposes was used. The study was split into three phases. Firstly, electrophysiologists delineated a well-defined structure in three patients (spinal canal). Secondly, observers delineated the VT-target in three patients based on case descriptions. To evaluate baseline performance, a basic workflow approach was used, no advanced techniques were allowed. Thirdly, observers delineated three predefined segments from the 17-segment model. Interobserver variability was evaluated by assessing volumes, variation in distance to the median volume expressed by the root-mean-square of the standard deviation (RMS-SD) over the target volume, and the Dice-coefficient.

Results:
Ten electrophysiologists completed the study. For the first phase interobserver variability was low as indicated by low variation in distance to the median volume (RMS-SD range: 0.02-0.02cm) and high Dice-coefficients (mean: 0.97±0.01). In the second phase distance to the median volume was large (RMS-SD range: 0.52-1.02cm) and the Dice-coefficients low (mean: 0.40±0.15). In the third phase, similar results were observed (RMS-SD range: 0.51-1.55cm, Dice-coefficient mean: 0.31±0.21).

Conclusions:
Interobserver variability is high for manual delineation of the VT-target and ventricular segments. This evaluation of the baseline observer variation shows that there is a need for methods and tools to improve variability and allows for future comparison of interventions aiming to reduce observer variation, for STAR but possibly also for catheter ablation.